Patent GB-903337-A (GB)
Title: Improvements relating to grinding machines
Inventor: JONES JOHN CYRIL
IPC: G05B19/04
Filed: 1959-06-02
Abstract: 903,337. Grinding; trueing grinding wheels. CHURCHILL MACHINE TOOL CO. Ltd. May 19, 1960 [June 2, 1959], No. 18819/59. Class 60.  Control equipment for a grinding machine comprises means for counting a predetermined number of grinding operations, means for initiating a trueing cycle and suspending the grinding operations after the predetermined number of grinding operations has been completed, means for recommencing grinding operations after the trueing cycle has been completed and means for providing a compensating feed to the grinding wheel during or after the trueing cycle. The equipment is applicable to machines having one or two stage gauging or diminishing feed sizing. In an arrangement for single stage gauging, operation of a push-button 12 energizes a start relay SR and a diminishing feed solenoid DFS operates a counter 13 and moves a head carrying a grinding wheel towards the workpiece, a contact controlling the dwell of the grinding wheel then being closed. On the workpiece reaching a predetermined size an electrical gauge closes a contact grl to initiate the retraction of the wheel head. After a number of such operations determined by the counter 13, a counter relay CR is energized to prevent further grinding operations by maintaining the grinding wheel in its retracted position, resets the counter to zero, and energizes a motor 4 connected by belts 3 to a lead screw 2 so as to traverse a block 5 carrying a diamond trueing tool 7 across the wheel. A rotary solenoid LTS is  then energized to effect a single downstroke of the diamond by rotating a worm 10 engaging a screw 11 in a plunger 6 carrying the diamond.  At the end of the movement of the block 5 to the left, the motor 4 is reversed to feed the diamond to the right and the solenoid LTS is again energized to move the diamond downwardly another stroke. The motor 4 is stopped at the end of the movement of the block to the right and a timing dwell is operated before the wheel head is moved forward, the gauge being fitted on a new oversize component. The dressing operation may be repeated by pressing a button RTB and the diamond can be raised or lowered by manual operation of switches 15,  16 energizing solenoids LTS, RTS. A compensating motor CM is actuated by the movement of the wheel head to give an adjustable ratchet feed to a feed hand wheel so that the workpiece is reduced in diameter until it reaches its finished size whereupon the motor CM is stopped. The wheel head is then retracted and grinding continues on a predetermined number of workpieces until the counter again instigates a trueing cycle. The electric circuit may be modified to enable two-stage grinding to be effected, the control being by electrically-operated hydraulic valves connected to the pressure and dashpot feed pipes in the feed cylinders and operated by an electrical gauge having contacts gr1 and gr2 which determine the extent of rough and finish grinding. After a predetermined number of workpieces have been ground, the wheel is trued as before and a diminishing feed slide is moved in stages at each retraction of the wheel to compensate for the reduction in size of the wheel. The compensation for reduction in size of the wheel may be effected without the use of a gauge by modifying the circuit so that at each traverse of the diamond the slide carrying the wheel head is moved during the trueing operation an amount equal to the depth of cut of the diamond. In a machine having two grinding wheels, the motor 4 moving the slide 5 may be controlled so as to move rapidly when the diamond is travelling from one wheel to the other.